It is currently the Taiheimeji era, during the rule of the Tokugawa shogunate. In this era, breasts mean everything. If you have breasts, you are guaranteed wealth and popularity, but if you lack them, you are rarely considered human. Inside the shogunate, there is a group of warriors that support the government—the Manyuu Clan, which helps raise the future big breasts. Written on a secret scroll possessed by the clan, there are said to be various techniques on how to grow big and beautiful breasts. Chifusa is the heir of the clan. However, she takes the secret scroll and runs away with it, hoping to fight against the cruel world that the Manyuu Clan has created…
